Threading apparatus



PrilZ, 1946- M. F. BoEcK r-:T A1.

THREADING APPARATUS Sheets-Sheet l Amal 2, 1946.

M. F. Bol-:CK ET AL 2,397,463

THREADING APPARATUS Filed June 21, 194s s sheets-sheet 2 `April 2, 1946. v M. F. BoEcK ET AL THREADING APPARATUS Filed June 21, 1943 5 Sheets-Sheet 5 flf ATTO EY.

Patented Apr. 2, 1946 UNITED STATES PATENT OFFICE Ohio, assignors tol The Sheffield Corporation, Dayton', Ohio, a corporation of, Ohio Application June 21, 1943, serial No. 491,635

9 Claims.

- This. invention relatesl to the cutting or nishing7 of. threaded or gauging members and the like. One objectof the invention resides inthe method` of. makingor iinishing a tapered thread, in which .the workpieceis rotated about its. own` axis whilein engagement at one side thereof with a rotatable serrated. tool which produces a progressive cutting Aaction in an annular direction around the, workpiece.

'Another object. resides in the methodof lapping atapered thread', which the thread is engaged along 'itsaxial length but at. only one sdeof the workpiece with a rotatable threaded lapping` tool, one of these parts having a movement eccentricl 'of thework axis. so Vas to .progressively lap the work-.in anv annular direction around thework.

Another object is. the. provision of apparatus for carrying out these methods. Y

A notherobject is .the provision of apparatus for finishing. a threaded. workpiece. embodying av rotatable work holder and a serrated finishing tool whichisarranged eccentric of the work axis and4 havngprovision for movement in a predetermined direction angularly related to the Work axis.

. Another. object is theprovision. of apparatus embodying a rotatable work holder, and a rotatable rtool holder. which is mounted in a support capable` of movement substantially transversely of the work axis and movable also at an angle to the work. axis corresponding to the taper angle of `the surface-tcbenishedon the work piece.

Other` objects andl advantages of theinvention willbe apparent from. the following description, the appended claims and the accompanying drawings,inwhich, n

d Fig. 1 is a. plan view ofan apparatus embodying orrfor carrying out the present invention; ,Fig.. 2 is a longitudinal vertical section of the apparatus shown inlFig. 1. d

Fig. 3 isanA enlargedview corresponding tothe left hand portionof Fig. 2`, with the tool holder in a retracted position;

Fig. f1 is a vsect'ionontheline,Il,-15 of Fig.- l;

Fig. 5 is a section on the line 5`5 of Fg..2;

Fig. 6 isan end view showing` the relativeengagement of. the workpiece andthe lappingtool;

Fig. 7 is a section on the line 'I-1 0f Fig. 2;

Fig. 8 is a section corresponding toFig. 7 but showing the lapping tool. at the opposite end of its limiter travel;

. a diagrammatic connections`;v .v l

. Fig. 101s a vertical section on the line Ill-I0 of Fig. 1; and

of the drive Fig..11..is adiagrarnmatic showing of the electrical. connections.

Referring more particularly to the drawings, in which the same reference numerals have beenapplied `to correspondingparts in the several views, I l) designates the mounting base or frame, below which the. drive motor and Agears are arranged, and on which is carried a work holder II,v a tool support l2 and ay drive shaft bearing, I3. tool` support `I2 carries a rotatable. nishingktool herein shown as a 'threaded tapered lappingplug, agthe inventionhas been. described' herein as particularly applicableior the lapping of tapered thread rings such. as ringgauges or the like." In lapping [a threaded plug, the lapping toolk would be,v a. threadedv ring, it. being ,apparent that other forms of lapp'ingtoolmayv ofcourse be substituted for the particular thread lap which has been shown. ,y

The worky ieee which .may be an. internally threaded ring having tapered threads, is carried for rotation about. its own axis. in the Work holder II; anduisrotated at a .suitable speed, as by a drivebelt l5oper`ating around pulleys IEand I'I (seeFi'gs. 2. and. 9). Thepulley I'l is d'rvenby pulley I8v from a drive motor. I9. The shaft 20 which carries one of the. gears IB also operates a gear v2I through. aV speed reducinggear box 22. .Rulley 2II is connectedby belt 23 to a pulley 2'4 whichis connected to the lapping toolas. will be presently described. The Arelative speedsof the pulleys .I6 `and 2liv `ispreferably such `that the workpiece is driven substantially fasterthan the lapping tool, the workpiece. and the lapping tool turning inopposite directions. It has been round. quite .satisfactory to have the workpiece turned at a speed of. about LR. P. M. with the lappin'gtool turned ata speed of about 20 R.,P. M.

The workpiece, designated by. numeral 26, which is shown. as a threaded ring gauge adapted for gauging,v pipe threads, is held in a. centered. relationwth respect to the work carrying arbor 21 byaneans of. clamps ,28. The arbor 2l is rotatably mounted by suitable bearings 28.in the work holder I I, the pulley I6 being secured to one end of the arbor. The work holder II isfastened as by means of suitable. securing screwsto the plate IIJ, The .work carrying arbor 21 is preferably hollow, having a cylindrical chamber 311.Av Normally the piston `:lil Vis in its retracted vor outer positionas illustrated in Fig. 2V and it maybe moved to that ,position bythe stem orhandle 35.

When the. workpiece is being mounted onv the end of the arbor 2,1, the Istemi. is pushednwardly to move the piston into the position shown in Ther Vposition with'y respect to the workpiece.

adjusted into a centered relationship on the arbor, and the clamps 28 are then tightened, and the centering plug 31 removed.

The pulley 24 is secured by means of a pin 39 to a hollow shaft 40 which is'rotatably journaled in the drive shaft bearing I3. Shaft 46 is `pro vvided with slots or grooves 4I which form guideways for rollers 42 rotatably carried on a pin 43 which is secured to a drive rod 44. Thisl rodis Vconnected by a flexible coupling 45 to the shaft section 46 which isfixed to tool holderor spindle 49 in which the lapping plug 43 is xed, as by a suitable set screw, not shown. The shaft section 46 Yis removably fixed in tool holder 49, which is supported by means of anti-friction bearings 55 for free rotation in the support I2. f

The support I2 is arranged vfor sliding movement on a carrier 52 so as to move'in a direction towards and from the workpiece. The carrier, which" is vpreferably an elongated.Y plate, is provided with guideways 53 which Vguide vthe base vportion 54 of the support I2. Suitable anti-friction rolls or balls 55V are interposed between the parts 53 and 54. The plate 52 is rotatably adjust-.- able on but xed to a plate 56, which is secured to a transversely extending plate 51'. This plate 51 isguided for movementA transversely of the axis of the work, in a mounting base 58, with Y suitable anti-friction balls or rollers 59 interposed between the parts 51 and 58. The arrange,-

' mentof the carrier 52 on the mounting Vbase 58 Y thus permits transverse movement of the tool,

and the arrangement of the tool support I 2 on the carrier permits movement of the tool in a depends onthe adjustment of the carrying plate 52 on the plate 56, this adjustmentpermitting the location ofthe guideways 53A sothey extend parallel to the v,desired taper angle of `the threads on the workpiece, and by taper angle of the threads Von the Vworkpiece is meant the angle between the work axis andA aplane touching the ends of all the threads at. one side of ther work. The adjustment of the. carrier plate 52V on the plate 55 is accomplished byrloosening the' fastening screws 60 which are threaded in the carrier plate 52and which are arranged in arcuate slots Vin the plate 55 concentric with the vertical axis of this plate. The carrier plate 52 can then be turned relatively to plate 56 to align the guide Ways 53 with the desired taper angle of the threads on'the workpiece. The screws 60 are then Vtight- Venedto rigidly hold the parts 52 and 55 against relative displacement.

Arranged preferablyY at the top of the toolsupport I2 is a handle 62 which theoperator may grasp in order to move Athe tool support, and consequently move the tool, into a desired working Move` ment of the tool, either ina direction transverse ofthe Work piece axis or in a direction towards or from the workpiece, is effected without interfering with the rotational drive ofthe tool, lsince the exible connection 45 permits misalignment of the axes of the tool and the rod 44, and the connection between the rod 44 and the shaft 4G permits, in .eiect, a telescopic movement of the rod 44 along the shaft 4,0 while maintaining a rotational drive connection. The operator is thus enabled, by grasping and moving the handle 52, to retract the tool to the right from the position shown in Fig. 2 to the position shown in Fig. 3. As shownin Fig. 1, the bearing housing I3 is laterally displaced from the axis of the Workfpiece, and the drive shaft 40 is at a slight angle to the work axis, corresponding preferably to the average taper angle of workpieces to be finished,

so that when the tool is operating the axis of the Vrod 44 will be approximately in alignment with the axis ofthe shaft 40. The axis of the rod 44, however, will be at a slight angle to the axis of the shaft section 46, since the' latter is positioned by 7, and 8 is made preferably of cast iron or otherv suitable material adapted for satisfactory lapping operation. Itis considerably longer than the length ofthe thread to be lapped on the workpiece and is of substantially smaller diameter thanthe threads in the workpiece. The threads on vthe lapping tool have the same pitch distance as the threads to be lapped on the workpiece. ,As shown, the larger end of the threaded lapping tool is small enough in diameter so that the lapping tool can move through the workplece'without jamming against it. In use, the operator, by grasping the handle 62, can move the lapping toolinto the workpiece and then, as the lapping tool is moved laterally with respect to the axis of the workpiece, the threads of the lapping tool are brought into contact with the threads von the workpiece. Before these threadsv engage, the drive motor is Astarted so thai-the workpiece and the lapping tool are turned, each on its own axis, these axes being parallel to one another but relatively spaced during the lapping operation. Since the tool support I2 is free to move towardsV and from the workpiece, the lapping tool will be drawn alongthe workpiece by reason of the threaded engagement that takes place at one side' of the lapping'tool with one side of the workpiece. The

lapping ytool is thus caused to travel along the workpiece inrone direction. or the other, so that `the thread on the workpiece is progressively lapped in an annular direction around the workpiece. As the line of contact varies vannularly around the workpiece, the threads on the workl piece are lapped until the desired size andiinish is obtained. A reversal in the direction of` rotation o'f both the Ylapping tool and the workpiece ,takes place automatically when these parts are in therelative positions approximately as shown in eration. VThis automatic reversal is effected'by limit switches and a reversble'motor, or anequivaient construction, as will be presently described. It will be apparent that as the axial movement of the lapping tool takes place, the axis ofthe tooly is simultaneously displaced laterally the exact arr'iour'itl required to maintainthe lapping tool in threaded engagement andv effective` lapping contact with the work, sincethe guidesc carrier -52 are arranged in exactvparallelism with the `justably threaded in alug 65 an-dheld'in adjusted posi-tionby a lock nut. 66; 'Ihelug Br-is xed on theplate |10 as shown in Figs. 1 and 10. The spring f?? Athus yieldingly urges the carrying means 52 andthe tool support vl2 in a direction to engage s the 'lapping tool with the work, and with a pressure determined by the-setting of thescrew 64.

The operator can readilyy move the tool against 'the' pressure of the spring 63by pushing on the handle 62 before he movesthe tool into the Work and the tool is then moved laterally and engaged with a yielding pressure when he releases the pushon the handle. The plate 51, as shown in Figs. 1 and l0 has -a side surface `68 parallel to the axis of the workpiece. This surface 6811s engaged by an adjustable stop 59 Vwhich prevents continued lapping on the/Work after the proper sizer is obtained, the stop 69" being previously set' into-a desired position', as by adjusting' the handle to move the threaded stem 1| along the lug 12. When the 'lapping tool is first brought into engagement with the workpiece' there? is a substantial space between the end of the `stop 69 and the side surface 68, but as thev lapping operation proceeds, and the workpiece islapped, the surface 68 'is moved over by the spring and nnally contacts the stop 69 which locates the lapping tool in iinal lapping position. If there aresome portions of the workpiece, due to a very slight eccentricity or uneven lapping, which require further lapping, those portions of the workpiece will continue to be lapped while the other portions of the workpiece, which have been lapped to nal size, will be held out of pressure contact with the lapping tool by means of the stop 69. With this stop properly set, excessive lapping such as would wear down the workpiece to an undesired extent,

is prevented. The operator is therefore relieved of the responsibility of determining exactly when the lapping operation is completed.

Limit switches which control the reversing of the motor after the predetermined amount of travel oi the lapping tool takes placeare controlled by switch operating discs 13 adjustably mounted so they can be set at predetermined positions on a stationary shaft 14 which is carried by a bracket 15. The bracket is fixed to the tool holder i2. These discs 13 operateswitch controls 16. The closing of these switches operates reversing relays 11 to control reversing switches 18. The reversing switches 18 change the phase relationship of the current supplied from a three phase source 19 to the motor I9. Start and stop switches 80 and 8| in a starting circuit are manually moved by the operator at the start and stop of any lapping operation. The starting circuit also includes a limit switch 82, operated by a stop 83 on the support I2, which insures stopping of the motor if the switch 16 should fail to d0 so,

While the form of apparatus and the method jof operation herein described constitutes a; preferr-ed Iembodimentf ofthe invention, itisrto be understood that the invention is not .limited to this precise form of .apparatus and method, and thatchanges may be made therein without departing Vfrom the scopeofrthe invention which is defined in the appended claims.

V`What is claimed is;

I. Apparatus for lapping taper threads of an internally threaded workpiece comprising a vwork holder; a threaded lapping tool having tapered threads and having an effective lapping portion longer than the thread length to be lapped and substantiaiiy smaller in diameter than the threads lapped, means for rotating the work holder, means for rotating the tool, means for maintaining the axis of the tool parallel to the work axis, means for 'periodically reversing the direction of rotation of the tool, and means for mounting the tool for free rectilinear movement in a predetermined direction at an angle to the axis of the workpiece corresponding to the taper angle of the threads on the workpiece, so thatmotion in such predetermined direction is dependent entirely upon engagement ofthe workpiece with the tool.

2. Apparatus of the characterfdescribed coniw prisin'g a work holder for holding a threaded workpiece, means for rotating' said holder about the work axis, la rotatable tool holder having a threaded lapping toolv of an effective length longer than the thread to be lapped, means for rotating the tool holder about an `axis parallel to the work axis, a support for said tool holder, means guiding said support for rectilinear movement substantially transversely of the work axis and for free rectilinear movement towards and from the work position but in a direction angularly related to the work axis, the motion of the support in the4 latter direction being unrestrained so that movement inA such direction takes place merely by action ofthe tool on the work, means for reversing the direction of rotation of the tool, a stop for limiting transverse movement of the tool holder, and spring means for yieldingly urging said support against said stop.

3. Apparatus of the character described comprising a work -holder, means for rotating the holder about the work axis, a rotatable tool holder, means for rotating. the tool holder, a support for said tool holder, av plurality of slides mounted one on the other with one of said slides carrying said support for mounting said tool holder for move ment in a plurality of predetermined directions one of which is substantially transversely of the work axis and the other of which is substantially towards and from the Work position but in a.

direction angularly related to the work axis, yielding means operable on said support to maintain yielding engagement of the tool with the work, and means for automaticallyreversing the direction of rotation of both the Work holder and the tool holder as predetermined positions of the tool holder are attained.

4. Apparatus for lapping taper threads of an internally threaded workpiece comprising a work holder, a threaded lapping tool having tapered threads and having an effective lapping portion longerithan the thread length to be lapped and substantially smaller in diameter than the threads lapped, a support for the lapping tool, carrying means for said support and providing for free endwise movement of the support in a direction angularly related to the Work axis in accordance with the taper angle of the threads, the movement of the support in such angularly related direction lceingY unrestrained so that motion of the support is merely vcaused by the inter engagement of the work and the tool, means for guiding the carrying means for movement of the carrying means in a direction transverse of the` work axis, and

means for rotating the toolandthe work at different speeds of rotation.

5. Apparatus for lapping taper threadsof an internally threaded workpiece comprising a Work .the tool axis parallel to the work axis and extending into therwork, and guide means for mounting said work holder and tool for horizontal free relative rectilinear movement towards and from one another in a predetermined direction correspond- -ing to the taper angle of the work, and means for ,yieldingly urging the tool laterally of the work axis to maintain yielding engagement with one side of the work.

' in its movements in the latter direction, means tool and the work at diierent relative speeds and in timed relation with one another, a stop for limiting transverse movement of the carrying means, and spring means for yieldingly urging said carrying means `against said stop.

' V6. Apparatus for lapping tapered workpieces comprising a rst holder and a second holder, one of said holders having means for supporting a taperedV threaded workpiece, a tapered threaded lapping tool carried yby the other holder, means for rotating said holders at relatively different speeds, means for maintaining the axes of said holders in parallelism and supporting said holders for free' relative movement towards 'andffrom one another so that one of the holders may be propelled by the Y threaded engagement of the workpiece and the Y ment'of the yieldingly urged holder.

7. Apparatus for taper'threading comprising a work holder, a threaded tapered tool having .threads of smaller diameter but the same pitch as the threaded portion of the workpiece, means for rotating said work holder and said threaded tool at relatively different speeds,emeans'for holding yieldingly urging the tool in said transverse direction so that the threaded portions of the tool and the workpiece produce relative movement generally in the direction of the workpiece axis, adjustaeble means :for limiting the lateral motion of the tool, and means for automatically changing the relative speeds of rotation after a predetermined relative movement of the tool alongthe workpiece to reverse the direction of travel.

9. Apparatus for lapping taper threads of an internally threaded'workpiece comprising a Work holder, a threaded tapered lapping tool tapered in accordance with the taper of the workpiece, means for -rotating the work holder concentric with the work axis, a tool head for the lapping tool, means for rotating the tool in said head at a speed dif'- fering from that of the'workpiece, and means for mountingthe tool head for free rectilinear mover ment in ya predetermined direction inclined 'to the work axis at an angle 4corresponding to the taper angle of the work,` a carrier supporting said MAX F. BOECK. HARRY L. RAUSCH.

8. Apparatus for lapping an internal thread on' 

